Need Schematic for Parasound HCA 2200 II

[mjctech]

I have a HCA 2200 II, One channel will blow a fuse after running at low volume for a short time. Then sometimes the overheat light will come on and after it cools down it works again. I can feel that the right side heat sink is hotter than the left. I checked it and the left side is running around 110 F. and the right is around 140 F. I checked the temp on the heat sensor bracket on both sides. I checked the power supply volts 74 +- ,


Please help
mike

[Leolabs]

Try to check the output offset voltage.

[carlmart]

Originally posted by mjctech
I have a HCA 2200 II, One channel will blow a fuse after running at low volume for a short time. Then sometimes the overheat light will come on and after it cools down it works again. I can feel that the right side heat sink is hotter than the left. I checked it and the left side is running around 110 F. and the right is around 140 F. I checked the temp on the heat sensor bracket on both sides. I checked the power supply volts 74 +- ,

Why don't you check the voltage between the emitters on one pair of output transistors to see if current is the same for both channels?

Perhaps there has been a slight deviation in VAS' trimpots. If that is so you should rather replace both trimpots with multiturn types.

Do you know if the output zobel is getting hot too? If so there might be some oscillation, but cure might be difficult without a service manual. Do get one as soon as possible, if not you will be too much in the dark.


Carlos